Failover: Return last tried server if it's still being tried

In the failover, we treat both KDC and LDAP on the IPA server as a single
"port", numbered 0. This was done in order to make sure that the SSSD
always talks to the same server for both LDAP and Kerberos.

However, this clever hack breaks when the IPA provider needs to establish an
GSSAPI encrypted LDAP connection because we're asking the fail over code to
yield a server while no server has yet been marked as tried. This triggers a
fail over for the KDC, so in effect, the TGT is received from second server.

If the second server is not available for some reason, the whole provider
goes offline.

The fail over needs to detect that the server asked for is still being
resolved and return the same pointer.

1 files changed, 6 insertions, 2 deletions

diff --git a/src/providers/fail_over.c b/src/providers/fail_over.c
index 002d6d578..7fed7cce1 100644
--- a/src/providers/fail_over.c
+++ b/src/providers/fail_over.c
@@ -75,7 +75,7 @@ struct fo_server {
     bool primary;
     void *user_data;
     int port;
-    int port_status;
+    enum port_status port_status;
     struct srv_data *srv_data;
     struct fo_service *service;
     struct timeval last_status_change;
@@ -686,12 +686,16 @@ get_first_server_entity(struct fo_service *service, struct fo_server **_server)
      * Otherwise iterate through the server list.
      */
 
-
     /* First, try primary servers after the last one we tried.
      * (only if the last one was primary as well)
      */
     if (service->last_tried_server != NULL &&
         service->last_tried_server->primary) {
+        if (service->last_tried_server->port_status == PORT_NEUTRAL) {
+            server = service->last_tried_server;
+            goto done;
+        }
+
         DLIST_FOR_EACH(server, service->last_tried_server->next) {
             /* Go only through primary servers */
             if (!server->primary) continue;